If we have pcap_free_datalinks(), use it. If not, then, on Windows,

just leak the list returned by pcap_list_datalinks(), as there's no
guarantee that if you have a library built with one version of the
MSVC++ run-time library, and it returns a pointer to allocated data, you
can free that data from a program linked with another version of the
MSVC++ run-time library.  (This is not an issue on UN*X.)

This should fix bug 2677.


git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@25668 f5534014-38df-0310-8fa8-9805f1628bb7

3 files changed, 52 insertions, 3 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index 37258ed201..ca97345c2f 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -522,7 +522,7 @@ install a newer version of the header file.])
 	   [Define to 1 if you have the `pcap_findalldevs' function and a pcap.h that declares pcap_if_t.])
 	  AC_CHECK_FUNCS(pcap_datalink_val_to_name pcap_datalink_name_to_val)
 	  AC_CHECK_FUNCS(pcap_list_datalinks pcap_set_datalink pcap_lib_version)
-	  AC_CHECK_FUNCS(pcap_get_selectable_fd)
+	  AC_CHECK_FUNCS(pcap_get_selectable_fd pcap_free_datalinks)
 	fi
 	LIBS="$ac_save_LIBS"
 ])
diff --git a/capture-pcap-util.c b/capture-pcap-util.c
index 129712d426..0d7024af5f 100644
--- a/capture-pcap-util.c
+++ b/capture-pcap-util.c
@@ -412,11 +412,34 @@ get_pcap_linktype_list(const char *devname, char **err_str)
 			linktype_list = g_list_append(linktype_list,
 			    data_link_info);
 	}
-	free(linktypes);
+#ifdef HAVE_PCAP_FREE_DATALINKS
+	pcap_free_datalinks(linktypes);
 #else
+	/*
+	 * In Windows, there's no guarantee that if you have a library
+	 * built with one version of the MSVC++ run-time library, and
+	 * it returns a pointer to allocated data, you can free that
+	 * data from a program linked with another version of the
+	 * MSVC++ run-time library.
+	 *
+	 * This is not an issue on UN*X.
+	 *
+	 * See the mail threads starting at
+	 *
+	 *	http://www.winpcap.org/pipermail/winpcap-users/2006-September/001421.html
+	 *
+	 * and
+	 *
+	 *	http://www.winpcap.org/pipermail/winpcap-users/2008-May/002498.html
+	 */
+#ifndef _WIN32
+	free(linktypes);
+#endif /* _WIN32 */
+#endif /* HAVE_PCAP_FREE_DATALINKS */
+#else /* HAVE_PCAP_LIST_DATALINKS */
 	data_link_info = create_data_link_info(deflt);
 	linktype_list = g_list_append(linktype_list, data_link_info);
-#endif
+#endif /* HAVE_PCAP_LIST_DATALINKS */
 
 	pcap_close(pch);
 	return linktype_list;
diff --git a/capture-wpcap.c b/capture-wpcap.c
index 66bfc3652a..90baec774b 100644
--- a/capture-wpcap.c
+++ b/capture-wpcap.c
@@ -111,6 +111,10 @@ static int 	(*p_pcap_list_datalinks)(pcap_t *, int **);
 static int	(*p_pcap_set_datalink)(pcap_t *, int);
 #endif
 
+#ifdef HAVE_FREE_DATALINKS
+static int 	(*p_pcap_free_datalinks)(int *);
+#endif
+
 typedef struct {
 	const char	*name;
 	gpointer	*ptr;
@@ -174,6 +178,9 @@ load_wpcap(void)
 #ifdef HAVE_PCAP_SET_DATALINK
 		SYM(pcap_set_datalink, FALSE),
 #endif
+#ifdef HAVE_PCAP_FREE_DATALINKS
+		SYM(pcap_free_datalinks, TRUE),
+#endif
 		{ NULL, NULL, FALSE }
 	};
 
@@ -503,6 +510,25 @@ pcap_list_datalinks(pcap_t *p, int **ddlt)
 }
 #endif
 
+#ifdef HAVE_PCAP_FREE_DATALINKS
+void
+pcap_free_datalinks(int *ddlt)
+{
+	g_assert(has_wpcap);
+
+	/*
+	 * If we don't have pcap_free_datalinks() in WinPcap,
+	 * we don't free the memory - we can't use free(), as
+	 * we might not have been built with the same version
+	 * of the C runtime library as WinPcap was, and, if we're
+	 * not, free() isn't guaranteed to work on something
+	 * allocated by WinPcap.
+	 */
+	if (p_pcap_free_datalinks != NULL)
+		p_pcap_free_datalinks(ddlt);
+}
+#endif
+
 #ifdef HAVE_PCAP_DATALINK_VAL_TO_NAME
 const char *
 pcap_datalink_val_to_name(int dlt)